The present invention relates generally to a rotary apparatus for shaping and dressing grinding wheels and, more specifically, to such apparatus with acoustic position sensing.
As shown in FIG. 5, a conventional grinding-wheel dressing apparatus includes a dresser shaft 130 supported on a housing 119 by bearings 115, 116 and 91. A cup-shaped dresser wheel 3 having a cutting edge 2 formed of diamond or the like is mounted at the left end of the dresser shaft 130 and abuts against a flange 123. Securing the dresser wheel 3 is a nut 28 engaging a threaded shaft 26. A portion of the dresser shaft 130 protruding from a left end wall of the housing 119 is sealed by a seal member 114. Interposed between the bearings 116 and 91 are an outer sleeve 117 and an inner sleeve 116. A nut 125 is threadedly engaged with a right end of the dresser shaft 130 and exerts on the inner race of the bearing 91 a force that renders the dresser shaft 130 immovable in an axial direction. The outer race of the bearing 91 is fitted into the right end of the housing 119 and is retained by a cover plate 112 secured by a bolt. Integrally formed with the hollow cover plate 112 is a screw shaft 112a. A conduit (not shown) is connected to the screw shaft 112a, and an end of a drive shaft (not shown) is connected within an opening 127 to the dresser shaft 130.
The rotary dresser device shown in FIG. 5 is used to shape a grinding wheel and thereby provide a high precision grinding surface. To enhance the efficiency of the shaping process, it is important to minimize contact (grinding allowance) between the dresser and the grinding wheel while obtaining the desired cutting surface. That objective is provided, typically, by an operator who relies on his hearing to detect the noise produced when the dresser wheel contacts the grinding wheel. Such human detection is low in accuracy and generally is accompanied by substantial error. Consequently, the efficiency of the shaping operation is deteriorated resulting in increased grinding costs.
The object of the present invention, therefore, is to provide a grinding wheel dressing apparatus which can produce highly accurate dressing and minimum loss of the abrasive grains used in expensive grinding wheels.